scabber
XS650 Guru
section8 If you go with the canadian needle start with the center slot I think this will work the best
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Am I on the right track? bs34's
- Thread starter section8joe
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- carburetors
After re-reading your 1st post, it does seem that you're still a bit lean in the pilot circuit. The hanging idle and decel popping indicate that. You can try your mix screws all the way out to 3 1/2 or 3 3/4 to see if that helps but much beyond that would indicate another jet change is called for. That would mean a 47.5 pilot but if that proves too rich, there's another way - the air jet. I don't know why more people don't take advantage of this tuning option. It's a way to fine tune the idle circuit on the BS34s. Changing the air jet doesn't have as much effect as changing the pilot so it's a way to get in between pilot size richness levels. In your case, if the 47.5 pilot proves too rich, go back to the 45 and reduce the air jet a couple sizes.
section8joe
XS650 Addict
Hey guys, it's been a few months and I've had some electrical/charging issues that have been solved. I'm trying once again to fine to the carbs. Here's a recap of my first post and the issue that I'm having.
The bike idles great. Idle doesn't hang when I let off the gas,no popping. Everything seems great until half throttle. When I'm really pushing the bike I seem to get two quick stutters(looses power) on the bike. Once I'm past that I can run full throttle with no issues. When letting off the gas from full throttle I get some popping from the exhaust. I was thinking maybe my mains were a little lean so I bumped them up to 140's and it made NO difference. These carbs are bs34 so no adjustment to the needles. My problems seem to be around 4 or 5,000 rpms. I was thinking about going up an other size on my pilots but I'm don't think the pilot circuit is causing the issue. I have the carbs off the bike and I'm waiting on some suggestions from you guys. What do you think?
The bike idles great. Idle doesn't hang when I let off the gas,no popping. Everything seems great until half throttle. When I'm really pushing the bike I seem to get two quick stutters(looses power) on the bike. Once I'm past that I can run full throttle with no issues. When letting off the gas from full throttle I get some popping from the exhaust. I was thinking maybe my mains were a little lean so I bumped them up to 140's and it made NO difference. These carbs are bs34 so no adjustment to the needles. My problems seem to be around 4 or 5,000 rpms. I was thinking about going up an other size on my pilots but I'm don't think the pilot circuit is causing the issue. I have the carbs off the bike and I'm waiting on some suggestions from you guys. What do you think?
There's a couple things you could try. First, a test run with the filters removed. These CV carbs don't work the best with a K&N style pleated element. They can disrupt the airflow, especially in the 4 to 5K range. If the filters prove to be the problem, I would recommend switching to UNI foam pods.
You could also try shimming your needle. This could tell you if a needle setting is causing your problem. On the BS34 needle, you can only shim it up or richer because it's spring-loaded on the top. Adding shims on top won't do anything. For testing purposes, move the thin washer above the e-clip to below it .....
This will raise the needle about ½ mm, or about half a clip change.
You could also try shimming your needle. This could tell you if a needle setting is causing your problem. On the BS34 needle, you can only shim it up or richer because it's spring-loaded on the top. Adding shims on top won't do anything. For testing purposes, move the thin washer above the e-clip to below it .....
This will raise the needle about ½ mm, or about half a clip change.
section8joe
XS650 Addict
Ill give it a try with the filter off and let you know how it goes. I'll keep the same pilots in too. I don't think this is a pilot issue.
Thanks!
Thanks!
+1 on shimming the needles, I do that when I overhaul BS34s, seems to fatten the midrange a bit which seems to be a good thing. Although I think it mainly tends to reduce an off idle stumble. 5twins suggests a DIFFERENT air filter not no air filter. CV carbs tend to hate no air filter operation. Hang the stock air filter/boxes back on it as an experiment?
section8joe
XS650 Addict
damn, I think I sold the old ones. I'll have to look. I may have a buddy with different filters.
Yup I got my 100. Have you picked a valve cover o-ring? I was looking at the square section and X section types.
Well back out to cutting firewood.
Well back out to cutting firewood.
I haven't tried to match the valve cover o-rings yet mostly because the originals seem to last darn near forever. I bought new ones from Mikes when I first fixed my bike up years back but the originals still sealed so I've yet to install the new ones. All I did was flip the old ones over in the covers to present a fresh side out.
Many times, the 3 hole covers will seep slightly when installed but if you pull and rotate them 120°, that usually fixes the leak. I don't know why but they just seem to seal better in one position as opposed to another.
Many times, the 3 hole covers will seep slightly when installed but if you pull and rotate them 120°, that usually fixes the leak. I don't know why but they just seem to seal better in one position as opposed to another.
section8joe
XS650 Addict
I found out that my bike had a bad ignition switch(causing a whole other set of problems). I swapped out the switch and the bike doesn't cut out anymore. It still needs a little carb tuning but that issue is gone. Thanks for the help everyone.
